Each year millions of tons of bromobutyl and chlorobutyl rubber are produced and used by the tire industry. The processes utilized to prepare such rubbers involve the use of halogenated solvents, often recycled between the production cycles of bromobutyl and chlorobutyl rubbers, which contain species such as Br, Br.sub.2, BrCl, and Br.sub.2 Cl in order of increasing toxicity as substituents on compounds. These species must be removed from the resulting rubber to levels that will not pose a health threat or hazard to handlers of the rubbers.
Several techniques exist to determine the level of halogens in rubber, however, each has deficiencies. For example, Electron Capture Detectors and Hall Electrolytic Conductivity Detectors may be used, but they afford no differentiation between Br and Cl species. Atomic Emission Detectors are capable of differentiating Br from Cl, but they are incapable of differentiating or determining the number of halogen atoms in a molecule such as Br from Br.sub.2. Because of the varying levels of toxicity of the various classes of halogen compounds, to obtain an accurate toxicity level, it is necessary to be able to differentiate between all halogenated species and quantify the levels of toxicity resulting from each.
U.S. Pat. No. 5,493,115 discloses a method for analyzing a sample for a compound of interest using mass analysis of ions produced by slow monochromatic electron beams. The sample itself is passed into an electron monochrometer and ions of at least a subpopulation of the molecules are formed. The ions are then passed through a mass analyzer to obtain a spectrum to determine if the ions in the spectrum contain ions from the analyte. The patent mentions that a gas chromatograph may be used to separate the sample prior to passing it into the electron monochrometer. No buffer gases are necessary.
There still is a need in the art for a method capable of accurately detecting the levels and types of the different toxic halogens in rubbers, specifically, bromobutyl rubbers, to ensure that rubber handlers are not exposed to unsafe levels of such toxins during production, handling, or further processing of the rubbers.
Though the instant invention is preferably utilized for bromobutyl rubbers, it can easily be extended to other halogen containing rubbers, resins, and chemicals by those skilled in the art, for example to chlorobutyl rubbers.